diff --git a/tests/test_templating.py b/tests/test_templating.py
index b60a592a..e65fe834 100644
--- a/tests/test_templating.py
+++ b/tests/test_templating.py
@@ -14,6 +14,7 @@ import pytest
 import flask
 import logging
 from jinja2 import TemplateNotFound
+import werkzeug.serving
 
 
 def test_context_processing():
@@ -346,6 +347,22 @@ def test_templates_auto_reload():
     app.config['TEMPLATES_AUTO_RELOAD'] = True
     assert app.jinja_env.auto_reload is True
 
+def test_templates_auto_reload_debug_run(monkeypatch):
+    # debug is None in config, config option is None, app.run(debug=True)
+    rv = {}
+
+    # Mocks werkzeug.serving.run_simple method
+    def run_simple_mock(*args, **kwargs):
+        rv['passthrough_errors'] = kwargs.get('passthrough_errors')
+
+    app = flask.Flask(__name__)
+    monkeypatch.setattr(werkzeug.serving, 'run_simple', run_simple_mock)
+
+    assert app.config['TEMPLATES_AUTO_RELOAD'] is None
+    assert app.jinja_env.auto_reload is False
+    app.run(debug=True)
+    assert app.jinja_env.auto_reload is True
+
 def test_template_loader_debugging(test_apps):
     from blueprintapp import app